Great job Alexander!
No issues getting this to work on our O365 environment, and love how intuitive the UI is. Especially the new RULES layout.
Note I do not have central admin access, so I requested the company I am working with (IT) enable the site collection app catalog for the specific site collectionn by getting them to run the below SP Powershell command:
Add-SPOSiteCollectionAppCatalog -Site https://jnj.sharepoint.com/teams/SITECOLLECTIONNAME
This only needs to be done if you do not see Apps for SharePoint in your Site Contents.
Then in Site Contents upload the file to the “Apps for SharePoint”
The back in Site Contents click NEW and click App
Then you should see the APP in top left (if sorted by newest) Click Add
Then you will see Modern DFFS in Site Contents
Now you can create a list, modern view and should see the DFFS icon at top of list.